The invention concerns a method for operation of an internal combustion engine supercharged by means of an exhaust gas turbo-supercharger, for vehicles, in particular passenger automobiles, as well as a device for putting the method into effect.
So-called normally aspirated engines, i.e., engines which operate without the assistance of superchargers, have, in general, performance characteristics whereby the course of the torque as plotted against the number of revolutions at full load is practically stationary. Thus, these engines provide through each load point of their performance characteristics directly calculable acceleration values for the vehicles driven by them.
Performance characteristics with full load curves have likewise been indicated for engines with exhaust gas turbo-superchargers. However, these full load curves indicate merely the maximum attainable torque which can be provided by the engine after specified acceleration times. In addition to these "stationary" full load curves which are present only when the interplay between cylinder and exhaust gas turbo-supercharger has come to a rest, there thus occur "momentaneous" full load curves which in particular in low speed ranges are much lower, and which, moreover, are dependent upon the starting point of the pertinent full load acceleration. This means that the instanteously attainable torque is considerably below the maximum attainable torque.
During the practical operation of an internal combustion engine with exhaust gas turbo-supercharger, the aforedescribed theoretical conditions result so that during a full load acceleration from a low load and speed range the desired maximum torque is reached with a great delay, whereby the supercharger speed, or more precisely, the rate of increase of the supercharger speed, is the criterion for the rapidity with which the engine attains its stationary full load condition.
It is true that the same conditions are present not only for the points of the full load line but also for all other points of the performance characteristics, so that at each acceleration only instantaneous load values are initially attainable which are lower than the stationary load points attainable after a distinct delay. However, in the load range below full load, the operator of a vehicle equipped with a turbo-engine can still compensate for insufficient torques by fuller actuation of the acceleration pedal, which is not possible when the full load point has been attained.